x86: change flush_tlb_others to take a const struct cpumask

Impact: reduce stack usage, use new cpumask API.

This is made a little more tricky by uv_flush_tlb_others which
actually alters its argument, for an IPI to be sent to the remaining
cpus in the mask.

I solve this by allocating a cpumask_var_t for this case and falling back
to IPI should this fail.

To eliminate temporaries in the caller, all flush_tlb_others implementations
now do the this-cpu-elimination step themselves.

Note also the curious "cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask)"
which has been there since pre-git and yet f->flush_cpumask is always zero
at this point.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>

1 files changed, 33 insertions, 28 deletions

diff --git a/arch/x86/kernel/tlb_64.c b/arch/x86/kernel/tlb_64.c
index f8be6f1d2e48..38836aef51b4 100644
--- a/arch/x86/kernel/tlb_64.c
+++ b/arch/x86/kernel/tlb_64.c
@@ -43,10 +43,10 @@
 
 union smp_flush_state {
         struct {
-                cpumask_t flush_cpumask;
                 struct mm_struct *flush_mm;
                 unsigned long flush_va;
                 spinlock_t tlbstate_lock;
+                DECLARE_BITMAP(flush_cpumask, NR_CPUS);
         };
         char pad[SMP_CACHE_BYTES];
 } ____cacheline_aligned;
@@ -131,7 +131,7 @@ asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs)
         sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
         f = &per_cpu(flush_state, sender);
 
-        if (!cpu_isset(cpu, f->flush_cpumask))
+        if (!cpumask_test_cpu(cpu, to_cpumask(f->flush_cpumask)))
                 goto out;
                 /*
                  * This was a BUG() but until someone can quote me the
@@ -153,19 +153,15 @@ asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs)
         }
 out:
         ack_APIC_irq();
-        cpu_clear(cpu, f->flush_cpumask);
+        cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
         inc_irq_stat(irq_tlb_count);
 }
 
-void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
-                             unsigned long va)
+static void flush_tlb_others_ipi(const struct cpumask *cpumask,
+                                 struct mm_struct *mm, unsigned long va)
 {
         int sender;
         union smp_flush_state *f;
-        cpumask_t cpumask = *cpumaskp;
-
-        if (is_uv_system() && uv_flush_tlb_others(&cpumask, mm, va))
-                return;
 
         /* Caller has disabled preemption */
         sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS;
@@ -180,7 +176,8 @@ void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
 
         f->flush_mm = mm;
         f->flush_va = va;
-        cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask);
+        cpumask_andnot(to_cpumask(f->flush_cpumask),
+                       cpumask, cpumask_of(smp_processor_id()));
 
         /*
          * Make the above memory operations globally visible before
@@ -191,9 +188,9 @@ void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
          * We have to send the IPI only to
          * CPUs affected.
          */
-        send_IPI_mask(&cpumask, INVALIDATE_TLB_VECTOR_START + sender);
+        send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender);
 
-        while (!cpus_empty(f->flush_cpumask))
+        while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
                 cpu_relax();
 
         f->flush_mm = NULL;
@@ -201,6 +198,24 @@ void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
         spin_unlock(&f->tlbstate_lock);
 }
 
+void native_flush_tlb_others(const struct cpumask *cpumask,
+                             struct mm_struct *mm, unsigned long va)
+{
+        if (is_uv_system()) {
+                cpumask_var_t after_uv_flush;
+
+                if (alloc_cpumask_var(&after_uv_flush, GFP_ATOMIC)) {
+                        cpumask_andnot(after_uv_flush,
+                                       cpumask, cpumask_of(smp_processor_id()));
+                        if (!uv_flush_tlb_others(after_uv_flush, mm, va))
+                                flush_tlb_others_ipi(after_uv_flush, mm, va);
+                        free_cpumask_var(after_uv_flush);
+                        return;
+                }
+        }
+        flush_tlb_others_ipi(cpumask, mm, va);
+}
+
 static int __cpuinit init_smp_flush(void)
 {
         int i;
@@ -215,25 +230,18 @@ core_initcall(init_smp_flush);
 void flush_tlb_current_task(void)
 {
         struct mm_struct *mm = current->mm;
-        cpumask_t cpu_mask;
 
         preempt_disable();
-        cpu_mask = mm->cpu_vm_mask;
-        cpu_clear(smp_processor_id(), cpu_mask);
 
         local_flush_tlb();
-        if (!cpus_empty(cpu_mask))
-                flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
+        if (cpumask_any_but(&mm->cpu_vm_mask, smp_processor_id()) < nr_cpu_ids)
+                flush_tlb_others(&mm->cpu_vm_mask, mm, TLB_FLUSH_ALL);
         preempt_enable();
 }
 
 void flush_tlb_mm(struct mm_struct *mm)
 {
-        cpumask_t cpu_mask;
-
         preempt_disable();
-        cpu_mask = mm->cpu_vm_mask;
-        cpu_clear(smp_processor_id(), cpu_mask);
 
         if (current->active_mm == mm) {
                 if (current->mm)
@@ -241,8 +249,8 @@ void flush_tlb_mm(struct mm_struct *mm)
                 else
                         leave_mm(smp_processor_id());
         }
-        if (!cpus_empty(cpu_mask))
-                flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
+        if (cpumask_any_but(&mm->cpu_vm_mask, smp_processor_id()) < nr_cpu_ids)
+                flush_tlb_others(&mm->cpu_vm_mask, mm, TLB_FLUSH_ALL);
 
         preempt_enable();
 }
@@ -250,11 +258,8 @@ void flush_tlb_mm(struct mm_struct *mm)
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
 {
         struct mm_struct *mm = vma->vm_mm;
-        cpumask_t cpu_mask;
 
         preempt_disable();
-        cpu_mask = mm->cpu_vm_mask;
-        cpu_clear(smp_processor_id(), cpu_mask);
 
         if (current->active_mm == mm) {
                 if (current->mm)
@@ -263,8 +268,8 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
                         leave_mm(smp_processor_id());
         }
 
-        if (!cpus_empty(cpu_mask))
-                flush_tlb_others(cpu_mask, mm, va);
+        if (cpumask_any_but(&mm->cpu_vm_mask, smp_processor_id()) < nr_cpu_ids)
+                flush_tlb_others(&mm->cpu_vm_mask, mm, va);
 
         preempt_enable();
 }